Nozzle for use with flying knife cutter in staple production



May 29, 1956 R. LE ROY KEEFE, JR 2,747,568

NOZZLE FOR USE WITH FLYING KNIFE CUTTER IN STAPLE PRODUCTION Filed Sept. 23, 1952 INVENTOR Z Roberb LeRoy Keefe Jr.

ATTORNEY United States Patent NOZZLE FOR USE WITH FLYING KNIFE CUTTER IN STAPLE PRODUCTION Robert Le Roy Keefe, Jr., New Castle, Deb, assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Application September 23, N52, Serial No. 311,061

2 Claims. (Cl. 164-60) This invention relates to the production of staple. More particularly, it relates to means for improving the quality of the product and to apparatus for facilitating the cutting of filaments on the run into staple with flying knife type cutters.

In the production of staple from continuous filaments, the running ends are commonly led to a cutter which is of the flying knife type. Directly above and below the cutter are nozzles. Usually the nozzle above delivers the yarn to the flying knife, and where a tube leading away from the knife is used, the staple passes through it to a collection device which generally is a bin of some kind. One of the important considerations in staple production is the length of time the knives may be used without replacement. It has been usually thought that off-quality staple was the result of improper cutting. It has now been found that certain imperfections are not traceable to the cutting but result rather at points before or beyond the cutting stage.

It is an object of this invention to prevent these imperfections. Another object is the provision of apparatus which permits the production of staple having a minimum number of neps. These neps are small knots resulting from the tangling of two or more filaments. A still further object of this invention is to provide apparatus which prevents damage to the filaments leading to nep formation.

These objects are accomplished by the provision of a nozzle which has at its exit end or entrance rounded interior edges. Hitherto, delivery tubes used with cutters in staple manufacture had square edged ends and it was considered an essential feature for best delivering and receiving of staple that the delivery and receiving tubes be square edged at the ends. The accompanying figures and the description below bescribe the invention in more detail.

Figure l is an elevation of the air jet or delivery tube of this invention;

Figure 2 is a cross-section of the cutter exit tube;

Figure 3 is a showing based on photomicrographs, of a part of a filament delivered or received through conventional tubes, and

Figure 4 shows how the tubes cooperate with a cutter such as the flying knife cutter described above.

As can be seen in Figure 3, the filament 1 that has passed through conventional tubes had been damaged. At location 2 there is a nick or a out where the sharp inside edge of the square nozzle has nicked the filament during the cutting operation. These nicks or rough spots on the filaments are troublesome, for the smooth surfaces of other filament sections cannot slide smoothly over these rough spots. Hence, filaments tend to pile up and tangle at these focal points to cause neps.

in most cases the filament bends sharply at the nick and forms a projection on which other filaments tangle to produce a nep. Occasionally, even where the action of the flying knife and the square edged nozzle may not nick the filament, a hook end it) may be formed by a jamming action of the knife at the sharp edge. Again the sharp bend of the hook end serves as a focal point on which other filaments tangle to form a nep. The presence of small knots caused by the taugling of two or more filaments is undesirable since these defects are magnified in the further handling of or the fabricating of the staple. In the absence of nicks, rough spots or hook ends, the smooth filaments readily slide over each other, entanglement is minimized if not altogether prevented and the staple is uniform.

This desired result is attained by use of the tubes 3 or 4 as the delivery or receiving tubes. As shown, the exit end 5 of the delivery tube 3 has rounded edges 6. These are immediately above the flying knife cutter. Continuous filament being jetted through the passageway 7 goes past the edges 6 without dilficulty. Even if the filaments drag against these edges there is no damageto the filaments. The same is true of the receiving tube 4. Here the entrance 8 is immediately below the cutter and the inner edges 9 are rounded. Any filament or staple thrown against these rounded edges is undamaged. The radius of the rounded contour is usually made equal to the wall thickness of the tube, but this is not essential. The tubes are usually made of stainless steel or a similar material which is hard or can be hardened to withstand wear over an appreciable period of time. For this reason it is preferred that metal tubes be of a metal having a hardness above 15 on the Rockwell C scale.

As shown in Figure 4, the delivery tube 3 with its passageway 7 is situated above knife cutter 11, and the exit tube 4 is located below knife cutter 11. The cutter 11 has a knife edge 12 or a plurality of knife edges which are of the fiying type, since the cutter 11 is rotated. One such knife edge 12 as shown in Figure 4 to show how the filaments are cut as they run from the delivery tube to the exit tube. It is at this location that the nicks or neps 2 shown in Figure 3 occur in the absence of the rounded surfaces 6 and 9.

The effectiveness of this invention is readily illustrated. Using the standard square nozzles the number of neps were 380 per grains of staple whereas, at the same cutter speed and other conditions equal, there were only 180 neps per 100 grains of staple when using the rounded nozzles of this invention. In another experiment at a higher cutting speed the number of neps was reduced from per 100 grains using the square nozzles to only 40 per 100 grains using the rounded nozzles. These reductions are very substantial and decidedly important, for, in conjunction with other improvements at other stages of staple manufacture, additional independent reductions are attainable leading to staple having 0-20 neps/ 100 grains. The improved quality is attained along with reduction in production costs, for continuity of the cutting operation is improved and the amount of staple produced in a given time is increased.

It is surprising that with the rounded edge nozzles the effectiveness of the blades in producing clean cuts is not decreased. With the nozzles of this invention there are no double length cuts per 100 grains of fiber, and the quality of the product is markedly improved.

Further, there is a marked reduction in cutter fluff. Cutter fluff is short length about to 4 inch in length. The fluff, of course, contributes to defects in spun staple yarn. It also enters the bearings on the cutter and necessitates frequent shutdowns for maintenance work. The reduction in cutter fluff attained in this invention increases bearing life and appreciably reduces the number of shutdowns.

The effects of this invention are surprising for still another reason in that the prior art in U. S. Patent 2,541,181 shows the damage sought to be avoided by this invention is obtained by rounding off the exit end of the delivery tube in a Beria cutter. Thus, in the cited instance the application of the rounded contour in the cutter exit tube aided in producing damaged fibers. In view of this, the efiects obtained in this invention are, indeed novel. The benefits of this invention are obtainable with any of the many filaments used in staple production. Such filaments include those of polyamides, acrylonitrile polymers, polyesters, regenerated cellulose, cellulose acetate, and vinyl chloride polymers.

Any departure from the above description which conforms to the present invention is intended to be included within the scope of the claims.

I claim:

1. In staple fiber cutting apparatus comprising a flying knife cutter having a horizontal cutting plane, a delivery tube above the cutter and an exit tube below the cutter in axial alignment with the delivery tube whereby filamentary material is directed vertically downward past the cutter, the improvement which comprises rounded interior edges at the exit of the delivery tube and at the entry in the exit tube.

2. Staple fiber cutting apparatus having a flying knife cutter disposed in a horizontal cutting plane, a delivery tube above the cutter and an exit tube below the cutter in axial alignment with the delivery tube whereby filamentary material is directed vertically downward past the cutter, said apparatus being characterized by rounded interior edges of the delivery and exit tubes adjacent the flying knife cutter. 

1. IN STAPLE FIBER CUTTING APPARATUS COMPRISING A FLYING KNIFE CUTTER HAVING A HORIZONTAL CUTTING PLANE, A DELIVERY TUBE ABOVE THE CUTTER AND AN EXIT TUBE BELOW THE CUTTER IN AXIAL ALIGNMENT WITH THE DELIVERY TUBE WHEREBY FILAMENTARY MATERIAL IS DIRECTED VERTICALLY DOWNWARD PAST THE CUTTER, THE IMPROVEMENT WHICH COMPRISES ROUNDED INTERIOR EDGES AT THE EXIT OF THE DELIVERY TUBE AND AT THE ENTRY IN THE EXIT TUBE. 